1. Field of the Invention
This invention relates to a time division drive recording apparatus and method. More specifically, this invention is suitable for the time division drive recording apparatus and method using an ink jet recording system that can record with high accuracy and at high speed.
2. Description of the Related Art
As copying apparatuses, information processing apparatuses such as word processors and computers, and communication apparatuses have become more and more widely used, image forming apparatuses which perform digital image recording using an ink jet system are rapidly becoming widely used. In such a recording apparatus, it is common to use a recording head (multi-head) in which plural recording elements are integrally arranged to improve recording speed. Ink discharge openings and liquid paths are integrally arranged to correspond to recording elements in the case of an ink jet system.
Printing a monochromatic high resolution image or a color image requires good coloring, tonality, uniformity and so on.
In a recording apparatus of the bubble jet system which discharges ink using thermal energy, among many kinds of ink jet recording apparatuses, a heat element is controlled by applying plural electric pulses to the heat element. By applying plural electric pulses or, in some cases, changing the width thereof, an ink discharge condition can be kept constant so printing quality can be maintained constant regardless of outside environmental conditions (e.g., temperature).
However, recently in an ink jet system not only high printing quality but also high recording speed are expected.
To control the heat element by applying plural pulses to improve printing quality requires much time for control because one dot must be formed by applying plural pulses, so it is a disadvantage in achieving high recording speeds.
A driver structure of conventional printing heads 50A to 50D is shown in FIG. 4. In FIG. 4, the driver structure for black recording head 50A is shown in detail, but the driver structures for cyan head 50B, magenta head 50C, and yellow head 50D are similar. Black printing data BKSi (CSi, MSi, YSi for the other heads) is transferred to a shift register 51 and it is once stored in a latch 52. By performing AND (logical product) of the data stored in the latch 52, common signals BEi1*, BEi2*, BEi3* and BEi4* commonly supplied to all heads and heat signal BkENB* (CENB*, MENB* and YENB* for the other heads), only designated heaters 54 can be driven by a transistor array 53. The symbol "*" designates low active.
Drive timing in a conventional recording apparatus is shown in FIGS. 5A-5H. FIGS. 5A-5H show that common signals (BEi1*, BEi2*, BEi3*, BEi4*) and heat signals (BkENB*, CENB*, MENB*, YENB*) are driven in a time division manner and a number of the heaters heated at the same time is limited in order to reduce consumption of electric power in an actual drive. As mentioned above, the heat signal comprises plural pulses to maintain printing quality.
In FIGS. 5E-5H, the manner of controlling by two pulses is shown. Each heat signal comprises a preheat pulse and a main heat pulse between which an interval period exists. The main heat pulse warms a heater for discharging ink by forming a bubble. The preheat pulse, however, is of insufficient duration to discharge the ink, but rather preheats the ink to control a bubble forming area.
However, this method takes a relatively large length of time because of the duration of the preheat period and the interval period, in comparison with a head drive method in which temperature control is not performed. As a result, in this method the drive time as a whole becomes too long as to diminish the high-speed drive of a printer. Moreover, it is desirable to select high resolution recording or standard resolution recording as needed.